Copepodid development of Pseudanthessius gracilis Claus, 1889 (Copepoda, Poecilostomatoida, Pseudanthessiidae), a copepod associated with Hydroides elegans (Haswell, 1883) (Annelida, Polychaeta) of Lake Faro (Messina, Italy) as obtained in the laboratory

The five copepodids of Pseudanthessius gracilis, a poecilostomatoid copepod (family Pseudanthessiidae) reared in the laboratory, are described. Sexual dimorphism occurs first in copepodid V, in which the maxilliped of the male, unlike that of the female, has an extra row of spinules. With regard to the true host our study has identified the polychaete Hydroides elegans.